*Indurated*:3. [to inure; accustom: to indurate oneself to privation and suffering][1]. 

To be made *hardy*: [capable of enduring fatigue, hardship, exposure, etc.; sturdy; strong][2] otherwise known as “hard as nails” (idiom)


  [1]: http://dictionary.reference.com/browse/indurate
  [2]: http://dictionary.reference.com/browse/hardy